If you start with a new Project Online instance, you will miss Work in Capacity Planning views. Previously, you saw Work displayed in all Project Server installations and in Project Online instances created in the past, without any additional actions. To see work assigned to a resource, you select resources in Resource Center and click on Capacity Planning.
If you work on a recently created instance, you will not see Work by default, even if assignment data is displayed in view Resource Assignments. So there will neither bars for Work nor any projects listed in the table. This is a side effect of a recent change. Now, the administrator can choose the level of reporting data for OData calls. See Configure rollup of timephased reporting data in Project Online for more information. For old instances, configuration is set to daily, so there is no change how data is displayed or can be used for reporting. For new instances, the default setting is Never. So there is no assignment data available for reporting until another option is selected. However, this has also an impact on view Capacity Planning. You need to select an option in PWA Settings - Enterprise Data - Reporting other than Never, to get Work visible in these views.
So in future, for any newly created instance, the administrator need to change this setting initially.